Trailing slash in URL breaks the auth flow

Describe the bug
We are using a third party OpenID provider that appends a slash to the redirect URL, e.g. scheme://my-domain.com/?code=... (note the trailing slash after my-domain.com). When this URL is opened by the browser, the user is taken back to the app but the auth flow gets stuck. Neither a result nor an error is produced. When the same URL without the trailing slash is opened, everything works fine. We are using AppAuth iOS Version 1.1.

Expected behavior
The AppAuth Android library handles this correctly and is ables to extract the authorization code from the URL, which i think should be the expected behavior.

Smartphone (please complete the following information):

• Device: iPhone 8
• OS: iOS 12.4
• Browser: stock browser

Additional context
We are using a thin wrapper around app auth for flutter (https://github.com/MaikuB/flutter_appauth) which should have no effect on the library's function.

The issue names no source file or test entry point. Reproduce the authorization flow with a redirect URL containing a trailing slash, then trace the iOS URL handling and add coverage showing that the authorization code is extracted and the flow completes without the slash-specific failure.